For numerous decades various material handling methods and techniques have been used for removing items from a conveyor in a selected order. U.S. Pat. No. 3,612,250 discloses a sorting conveyor system for distributing address-coded packages to various sorting stations. U.S. Pat. No. 1,217,988 teaches an early prior art technique for sorting washed laundry which is tagged and placed on a conveyor and dropped therefrom at a selected station. In U.S. Pat. No. 4,036,365 a conveyor system for an industrial laundry sorts garments which are identified and then dropped at stations but not on metal hangers.
In U.S. Pat. No. 4,239,435 a more recent attempt to satisfy the requirements of the commercial laundry industry for sorting and arranging garments is taught. In the '435 patent, hanger-supported garaments are randomly placed on a sorting conveyor which moves along a closed-loop path past a plurality of receiving stations, each receiving station identifies the garment passing thereby and released it at the appropriate station by dropping the hangered garment onto a secondary conveyor by a releasing structure controlled by a rotary solenoid. The apparatus used according to the '435 patent is complex and expensive and the system disclosed has found little acceptance in the commercial laundry industry.
Recent U.S. Pat. No. 4,991,719 teaches another commercial laundry sorting system of randomly positioned items on the sorting conveyor. The computer system which controls this conveyor is complex and drives the conveyor bi-directionally to achieve reduced movement time of the conveyor between drop-off stations. The pick-off mechanism in this patent is a robotic control arm which picks the hangers off the sorting conveyor from only one side and then deposits them on an adjacent unloading conveyor.
While there are sophisticated sorting conveyor systems, as typified in the last two mentioned patents above, the fact remains that practically all commercial laundries still sort manually. Most commercially cleaned garments include a conventional identification marking affixed thereon, and can be readily identified manually or by a bar code reader. The garments are initially sorted by routes which includes various customers. The garments are again sorted and placed on another conveyor grouping the garments by a customer account. A third manual sorting operation is then required to sort all the garments of a particular customer so that they will be grouped for the particular employees of that customer and preferably will be in a selected sequence with respect to garments for other employees of that same customer.
Manual garment sorting as just described has a number of significant drawbacks. First, the accuracy of the manual sorting procedure is a function of human frailties, which in turn means the sorting accuracy is influenced by considerations outside of the commercial laundry employer. Extremely high sorting accuracy is required, since the cost of replacing one of the clean garments improperly sorted and delivered to the wrong customer can practically offset the profits otherwise realized by the laundry for cleaning and sorting 100 other garments. Secondly, manual sorting of garments is very labor intensive as described above, and therefore is a substantial expense factor. In view of the number of repeated sorting operations described above and the multiplicity of conveyors required for each sorting operation, a good deal of floor space is required to perform this operation. The present invention provides a very compact sorting conveyor with twice the number of drop-off stations per lineal foot of conveyor due to the fact that two drop-off stations, one on each side can be located at the same conveyor station. The modular design of the conveyor allows the inclusion of one or more sorting sections to be included in the conveyor thereby allowing a range of drop-off stations from sixteen or multiples thereof.
It is therefore the principal object of the present invention to provide a low cost constant speed sorting conveyor which can accommodate an infinite range of sorting stations.
Another object of the present invention is to provide a constant speed sorting conveyor which has a high density of sorting stations located on both sides of the conveyor.
Another object of the present invention is to provide a constant speed sorting conveyor and has a very simplified transfer mechanism for each sorting station which has a high degree of reliability.
Another object of the present invention is to provide an improved technique for sorting garments on a sorting conveyor wherein the garments are identified by radio transponder devices affixed to the garments.
These and further objects and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.